Conduction-band electron effective mass in Zn _0.87 Mn _0.13 Se measured by terahertz and far-infrared magnetooptic ellipsometry

We determine the electron effective mass parameter m* =0.086±0.004 m0 of thin-film n -type low-chlorine-doped Zn0.87 Mn0.13 Se with free-charge-carrier concentration N=4.5× 1017 cm-3 and optical mobility μ=300±20 cm2 (V s) using magneto-optic generalized ellipsometry in the terahertz and far-infrared spectral domain for wave numbers from ω=30-650 cm-1. The room-temperature measurements were carried out with magnetic fields up to 3 T. We employ synchrotron and black-body radiation sources for the terahertz and far-infrared spectral regions, respectively. Comparison with previous experimental results from samples with considerably higher free electron density and theoretical calculations suggest that our value is sufficiently unaffected by band nonparabolicity and provides a good approximation of the Γ -point conduction band mass in Zn0.87 Mn0.13 Se. We further provide optical phonon mode parameters and the high-frequency dielectric constant.